In the past drill string elements were assembled at the surface to include bent subs and the like and, when installed in a well, were manipulated down hole to accomplish the desired effect. The down hole assembly was withdrawn from the well to make adjustments or element changes after one effect was achieved to prepare for the well course controls to follow and the drill string was again installed in the well. These round trips were costly in time and resources.
More recently slightly bent drill string elements were used, in conjunction with down hole drilling motors, to deflect the progressing well bore then the drill string was rotated during subsequent drilling activity to nullify the effect of the bent element for further well bore direction control. This strained the lower assembly of the drill string but the result was sustainable and accepted in light of the economies realized.
Still more recently, drill string elements have been supplied which respond to signals from the surface to change the down hole assembly between straight and directional drilling configurations. The lower portion of a drill string is commonly quite stiff compared to the upper portion due to the use of drill collars between the bit and the upper drill string portion. The well bore could be deflected at a rate too severe for the stiffer portions of the drill string to follow through unless they are made part of a flexible assembly. My copending U.S. patent application Ser, No. 267,563 represents a bendable element of this type.
There is a long standing need for methods to actuate bendable drill string elements as they approach the point of aggressive well bore deflection without negating the effects of those elements below that are already deflected so that a general curvature of the stiffer portions of the drill string results to negotiate the deflected well bore.
It is therefore an object of this invention to provide methods to utilize bendable drill string elements and down link commands from the surface to bend those elements in succession as drilling processes bring them to selected locations in the well to form a generally curved down hole assembly to fit the curvature of the well bore being deflected.
It is another object of this invention to provide methods to manipulate bendable drill string elements by combining elements that respond individually to selected drilling fluid flow rate encoding at the surface.
It is still another object of this invention to provide bendable drill string elements that can be controlled from the surface to bend individually to negotiate well bore curves and by further individual manipulation, controllable from the surface, to straighten again once through the bore curve.
It is still another object of this invention to provide bendable drill string elements that can be individually bent to negotiate a well bore curved in a first plane, straighten out after negotiating the curve, and again be deflected to form or to follow a well bore curved in a plane different from the plane of the first curve.
These and other objects, advantages, and features of this invention will be apparent to those skilled in the art from a consideration of this specification, including the attached claims and appended drawings.
From the foregoing, it will be seen that this invention is one well adapted to attain all of the ends and objects hereinabove set forth, together with other advantages which are obvious and which are inherent to the method.